RELEASE NOTES: JDK 24

javac Accepts class Files With Any Number of Entries in RuntimeVisibleParameterAnnotations and RuntimeInvisibleParameterAnnotations Attributes

The Java Virtual Machine Specification is permissive regarding the number of entries of the RuntimeVisibleParameterAnnotations and RuntimeInvisibleParameterAnnotations attributes in the class file format. The javac tool was less permissive, and was rejecting class files that had a different number of entries than javac expected.

As of JDK 24, this is fixed, and javac now accepts class files with any number of entries in the RuntimeVisibleParameterAnnotations and RuntimeInvisibleParameterAnnotations attributes. A compile-time warning is produced if the content of the attributes cannot be mapped to the corresponding method's parameters.

HttpClient 100-continue Timeout

java.net.http.HttpClient would previously timeout if a server didn’t respond to a request which included a Expect: 100-Continue header. 
This release updates HttpClient to send the request body if the server doesn’t respond and brings the implementation in line with RFC 9110

Deprecate jstatd for removal

The jstatd tool is deprecated, for removal in a future release. jstatd is an RMI server application which monitors HotSpot VMs, and provides a remote interface for jstat. This will not affect usage of jstat for monitoring local VMs using the Attach API.

MethodTypeDesc.resolveConstantDesc Throws ClassNotFoundException instead of TypeNotPresentException

In previous releases, MethodTypeDesc.resolveConstantDesc threw an unchecked TypeNotPresentException instead of a checked ReflectiveOperationException when a component class was not found. This behavior is now corrected to throw a ClassNotFoundException, conforming to the specification.

Code that previously handled TypeNotPresentException in addition to ReflectiveOperationException can consolidate the exception handling into the existing ReflectiveOperationException handling.

SunPKCS11 provider is enhanced to use CKM_AES_CTS mechanism if supported by native PKCS11 library

The SunPKCS11 provider has been enhanced to support the following AES CTS transformations for the Cipher service type:

• AES/CTS/NoPadding
• AES_128/CTS/NoPadding
• AES_192/CTS/NoPadding
• AES_256/CTS/NoPadding

The Addendum to NIST Special Publication 800-38A defines three variants of Ciphertext Stealing for CBC mode: CBC-CS1, CBC-CS2, and CBC-CS3. To ensure interoperability with SunJCE and Kerberos which use the CS3 variant, the SunPKCS11 provider needs to know the variant implemented by the underlying PKCS #11 library and convert the data if it is not in the CS3 variant. A new SunPKCS11 provider configuration attribute named cipherTextStealingVariant is introduced and must be set with any of the following values: CS1, CS2 or CS3 to indicate the CTS variant of the underlying PKCS #11 library, except for NSS as it is known to be CS1. Otherwise, the PKCS #11 CKM_AES_CTS mechanism is disabled.

Disable "best-fit" Mapping on Windows Command Line

Command line arguments to the Java launcher are no longer converted with Windows' "best-fit" mapping when the arguments include unmappable characters for the ANSI code page. This mapping has been intervening in the Java launcher's argument parsing. Unmappable characters are now replaced with the default replacement character, such as '?' in some cases. For rare cases, where applications need those unmappable characters on the command line, select UTF-8 in Windows Regional Settings.

The `LockingMode` Flag, Along With The `LM_LEGACY` And `LM_MONITOR` Modes Are Deprecated

A new lightweight locking mechanism for object monitor locking was introduced in JDK 21 under JDK-8291555. The LockingMode flag was introduced to allow selection of this new mechanism (LM_LIGHTWEIGHT, value 2) in place of the default mechanism (LM_LEGACY, value 1). In JDK 23, the LockingMode default was changed to LM_LIGHTWEIGHT.

In JDK 24, the LockingMode flag, along with the LM_LEGACY (1) and LM_MONITOR (0) modes are deprecated. The default locking mode LM_LIGHTWEIGHT will be the only internal implementation that is supported when these locking modes become obsolete in a future release.

This is not expected to change any semantic behavior of Java monitor locking and it is expected to be performance neutral for almost all applications.

Document Standard Hash and MGF Algorithms for RSASSA-PSS Signature

A new section for PSSParameterSpec algorithm names has been added to the Java Security Standard Algorithm Names specification. This section lists the standard hash and message generation function (MGF) algorithms that can be specified when initializing an RSASSA-PSS signature with a PSSParameterSpec object.

Reflective Invocation of VarHandle Signature Polymoprhic Methods Throws UnsupportedOperationException

Reflectively invoking VarHandle signature polymorphic methods is specified to throw UnsupportedOperationException. However, the implementation previously threw UnsatisfiedLinkError in such case. The behavior was adjusted to conform to the specification.

NumberFormat Supports IntegerOnly Parsing With Suffix

DecimalFormat, when the format expects a suffix, now parses correctly when the parse value contains a decimal symbol and isParseIntegerOnly() would return true. Previously, parsing would fail for such cases and the correct value never returned.

For example, in the following snippet, 5 will now be returned by the parse(String) invocation, instead of a ParseException thrown.

` NumberFormat fmt = NumberFormat.getPercentInstance(Locale.US); fmt.setParseIntegerOnly(true); fmt.parse("500.55%"); `

Distrust TLS Server Certificates Anchored by Entrust Root Certificates and Issued After Oct 2024

The JDK will stop trusting TLS server certificates issued after October 2024 and anchored by Entrust root certificates, in line with similar plans recently announced by Google and Mozilla. The list of affected certificates includes certificates branded as AffirmTrust, which are managed by Entrust.

TLS server certificates issued on or before October 31, 2024 will continue to be trusted until they expire. Certificates issued after that date, and anchored by any of the Certificate Authorities in the table below, will be rejected.

The restrictions will be enforced in the JDK implementation (the SunJSSE Provider) of the Java Secure Socket Extension (JSSE) API. A TLS session will not be negotiated if the server's certificate chain is anchored by any of the Certificate Authorities in the table below and the certificate has been issued after October 31, 2024.

An application will receive an Exception with a message indicating the trust anchor is not trusted, for example:

` TLS server certificate issued after 2024-10-31 and anchored by a distrusted legacy Entrust root CA: CN=Entrust.net Certification Authority (2048), OU=(c) 1999 Entrust.net Limited, OU=www.entrust.net/CPS_2048 incorp. by ref. (limits liab.), O=Entrust.net `

If necessary, and at your own risk, you can work around the restrictions by removing "ENTRUST_TLS" from the jdk.security.caDistrustPolicies security property in the java.security configuration file.

The restrictions are imposed on the following Entrust Root certificates included in the JDK:

You can also use the keytool utility from the JDK to print out details of the certificate chain, as follows:

keytool -v -list -alias <your_server_alias> -keystore <your_keystore_filename>

If any of the certificates in the chain are issued by one of the root CAs in the table above are listed in the output you will need to update the certificate or contact the organization that manages the server.

SSLSessionContext clarification regarding timeout limit

The javadoc for SSLSessionContext has been reworded to make it clear that when the timeout limit is exceeded for a session, the object is marked so that future connections cannot resume or rejoin the session. Active sessions can continue to be used so long as resume and rejoin operations are not attempted.

Linux desktop GTK2 support is removed

JDK's java.desktop module has internal code that interoperates with multiple versions of the GTK platform library. This is primarily to support the Swing GTK LookAndFeel.

The JDK previously included support for interoperating with the GTK 2 version of the library, which is reaching the end of its life. GTK 3 long ago superseded it and is supported by JDK as the preferred default, in which case to use GTK 2, apps must request it using the jdk.gtk.version System property. And since many recent distros make GTK 2 only an optional install, it may require extra work to use it, and future distros will likely not provide any way to install it.

Since all versions of Linux to be supported by JDK 24 provide GTK3, GTK2 support in JDK is now removed.

Setting the jdk.gtk.version System property to 2 or 2.2 will no longer have any effect, GTK 3 will be loaded.

The `ClassLoadingMXBean` and `MemoryMXBean` `isVerbose` Methods Are Now Consistent with Their `setVerbose` Methods

The ClassLoadingMXBean::setVerbose(boolean enabled) method will set class+load* logging on log output stdout to level info if enabled is true, and to level off otherwise. In contrast, the isVerbose method would check if exactly class+load logging was enabled at the info level on any log output. This could result in counter-intuitive behavior when logging class+load=info to a file via the command-line, as it caused isVerbose to return true, even after a call to setVerbose(false) had been made. A similar problem existed for the MemoryMXBean::isVerbose method. Starting with this release, the behavior is as follows:

• ClassLoadingMXBean::isVerbose will return true only if class+load* logging (note the wildcard use) has been enabled at the info level (or above) on the stdout log output.
• MemoryMXBean::isVerbose will return true only if gc logging has been enabled at the info level (or above) on the stdout log output.